Finding New Targets by Proteomic Approaches (InnovRT1)

Context: Rhaboid tumors (RT) are aggressive cancers of young infants, exposed to the toxicity of heavy treatments often ineffective, which justifies the need to identify new treatment strategies. These tumors are characterized by the biallelic alteration of SMARCB1 gene, encoding one of the subunits of the SWI/SNF complex, a chromatin remodeler. These mutations are the only ones found in these very stable cancers, which offers few therapeutic targets that can be identified by genomic techniques. They are morphologically undifferentiated and pluriphenotypic, suggesting the existence of a cellular diversity still poorly described. To advance on these questions, the investigators' laboratory has developed a model of genetically engineered mouse model spontaneously developing RT, biologically very similar to their human counterparts.

Objectives and methods: The investigators' project aims to describe the proteomic and phosphoproteomic signatures of these tumors, so far described at the genome and transcriptome level; an integration of these pangenomic / pan-proteomic studies will reveal the most relevant features to target. The investigators will fully characterize the proteomic and phosphoproteomic landscape using mass spectrometry on a cohort of clinically, radiologically and histopathologically annoted ATRT, for which methylome and RNAseq profiling will also be done. The investigators will describe the proteomic features of each molecularly defined subgroups, and aim to correlate RNAseq changes with proteomic features.

Patients will be included if they or their legal representative have given a consent to such a study, and if frozen material is stored at Necker Hospital.

Expected results: This analysis helps to identify how to articulate several innovative therapeutic approaches, taking into account both the diversity of the cells to be treated, and the real targets, proteins, to inhibit or restore.

Inclusion criteria

• Aged 0-17 years old
• Rhabdoid tumor, treated in oncology departments in Ile de France
• frozen samples collected in usual care
• parents' agreement for samples collection in usual care

Exclusion criteria

• Unconfirmed diagnosis of Rhabdoid tumor with molecular analyses Samples
• paraffin embedded tissues